My house was built in 1958 with metal piping. I purchased the house in 2008 and the previous owner replaced the kitchen sink with PVC piping. The connection of PVC to metal has a slow leak, and just changing the washer didn't fix. What can I do to fix this leak quick, easy, and inexpensive?

If the metal pipe you are talking about is chrome plated, it may be corroded too far and is collapsing. You may have to cut back the chrome pipe .Have you tightened the fitting well? Are you sure the fitting isn't cross threaded?One possible solution, would be to unscrew the nut, apply a generous bead of silicone so it squishes out when you tighten the nut. Then wait a couple of hours and try the drain. Hope it works.

Depending on the size of the metal pipe, you can purchase a shielded coupling... see image... works for most any transition... ;)

Measure metal pipe diameter and then go to a local plumbing supply store so you can be sure they will have what you need.

Mark